Looks like you've picked up some kind of infection. Since you say it still tastes good, if it were me, I'd transfer by racking from underneath the film into a new carboy and add potassium sorbate and potassium metabisulfite to knock down whatever is growing in there. It won't reverse any...
You would need to have 6 one gallon batches ready at the same time to pull this off I think. If you did them in succession, there will be too much head space in the 5 gallon carboy while waiting for other batches to be ready to transfer.
Before setting to lager fermentation temp, double check to make sure that your kit does indeed come with a lager yeast. Its my understanding that some of the coopers lager kits come with lager yeasts and others come with ale yeasts...